Blood plasma proteome analysis reveals biological mechanisms and potential biomarkers underlying feed efficiency in...

Feed efficiency, usually assessed by residual feed intake (RFI) and residual intake and gain (RIG), is a key trait for enhancing the profitability and sustainability of livestock systems. Although several genes linked to feed efficiency have been identified, the molecular mechanisms underlying this trait are not well understood. This study identified potential biomarkers and molecular mechanisms for feed efficiency in Texel ewes using a proteome approach. Thirty-nine ewes were evaluated in a feedlot to calculate RFI and RIG. Blood samples of a subset of 12 animals at the extremes of the feed efficiency range (six low-efficiency and six high-efficiency) were used for proteomic analysis. Differentially abundant proteins between the groups (absolute fold change ≥ 2; p < 0.05) were used for protein-protein interaction (PPI) network analysis using the STRING tool and functional enrichment analysis using the DAVID tool. Proteomics analysis detected 2,580 proteins; of these, 35 were differentially abundant between the high- and low-efficiency groups. PPI analyses revealed proteins encoded by the AHSG, PLG, CP, AFM, KNG1, LTF, ITIH2, and ITIH3 genes to be important nodes based on their centrality and interactions. Functional enrichment analysis identified ferroptosis, iron transport, copper binding, phospholipid metabolism, ATP binding, and endopeptidase inhibitor activities as significant terms, which may potentially contribute to feed efficiency. The findings provide new insights into the molecular mechanisms underlying feed efficiency in sheep and contribute to identifying potential biomarkers that may support future genomic selection strategies aimed at improving the efficiency and sustainability of sheep production.